248 DESCRIPTION OF CHALK CORALS. 
a single specimen in probably an early stage of growth, no opinion can be offered 
respecting either genus or species, and a right determination of the coral must 
consequently be left to future research. 
Tab. XVIII. figs. 14 to 28. 
The coral next to be noticed agrees in some respects with certain species of 
Oculina ; and the comparative observations will be chiefly confined to that genus. 
It consists of small amorphous masses, the largest (fig. 14) of the seven speci- 
mens examined being only |? inch in height and 1} in breadth. From a base 
(fig. 15, +-) which presented no expanded layer, but was moulded apparently on 
an irregular perishable surface, sprang one or more primary stems, that progress- 
ively enlarged upwards ; and from their sides issued subordinate shoots, the whole 
being united by external additions. The main branches as well as the oftshoots 
were traversed throughout by hollows or stellated cavities, often of large dimen- 
sions, but no doubt could be entertained that the former had once been occupied 
by lamellz, traces of their existence being clearly detectable, as will be shown in 
a subsequent paragraph. A comparison of figures 14 & 16, which express fully 
these characters with Esper’s' delineation of Oculina virginea of Lamarck, &c. 
would lead to the supposition that the fossil and recent corals were generically 
allied ; and Mr. Gray has recently stated, that the older branches of Oculina vir- 
ginea often become tubular*. The large hollows in Esper’s delineation, however, 
arose apparently from the removal of extraneous bodies, the specimen from which 
it was taken being stated to be ‘‘ einer rindenférmigen Mass*;” and an analogous 
mode of growth with the encrusted substance is shown in figure 3 of his tab. 12. 
In the genus Oculina moreover nothing approaching to a persistent, main, stellated 
cavity exists ; such a structure constituting an essential difference between it 
and the Dendrophyllia of M. De Blainville. The nature of the abdominal cavities 
and the mode of producing young hollows in the two zoophytes offer other di- 
stinctions. Among existing Oculine the cavities have great uniformity of cha- 
racter and dimensions in the same specimen, the changes due to growth being 
generally small; and the interior exhibits no signs of irregularity or peculiarity 
in progressive development. The greatest variations in size occur in Oc. prolt- 
' Esper, Pflanzenthiere, Madrep. oculata, tab. 13. 
* Annals Nat. Hist., Feb. 1847, vol. xix. p. 123. 
* Op. eit. Erster Theil, p. 108. 
